Based on the full BaBar data sample of 466.5 million BBbar pairs, we presentmeasurements of the electron spectrum from semileptonic B meson decays. We fitthe inclusive electron spectrum to distinguish Cabibbo-Kobayashi-Maskawa (CKM)suppressed B -> Xu e nu decays from the CKM-favored B -> Xc e nu decays, andfrom various other backgrounds, and determine the total semileptonic branchingfraction BR(B -> X e nu) = (10.34 +- 0.04_stat +- 0.26_syst)%, averaged overB+- and B0 mesons. We determine the spectrum and branching fraction forcharmless B -> Xu e nu decays and extract the CKM element |Vub|, by relying onfour different QCD calculations based on the heavy quark expansion. Whileexperimentally, the electron momentum region above 2.1GeV/c is favored, becausethe background is relatively low, the uncertainties for the theoreticalpredictions are largest in the region near the kinematic endpoint. Detailedstudies to assess the impact of these four predictions on the measurements ofthe electron spectrum, the branching fraction, and the extraction of the CKMmatrix element |Vub| are presented, with the lower limit on the electronmomentum varied from 0.8GeV/c to the kinematic endpoint. We determine |Vub|using each of these different calculations and find, |Vub| = (3.794 +-0.107_exp +0.292-0.219_SF +0.078-0.068_theory)*10^{-3} (De Fazio and Neubert),(4.563 +- 0.126_exp +0.230-0.208_SF +0.162-0.163_theory)*10^{-3} (Bosh, Lange,Neubert, and Paz), (3.959 +- 0.104_exp +0.164-0.154_SF+0.042-0.079_theory)*10^{-3} (Gambino, Giordano, Ossola, and Uraltsev), (3.848+- 0.108_exp +0.084-0.070_theory)*10^{-3} (dressed gluon exponentiation), wherethe stated uncertainties refer to the experimental uncertainties of the partialbranching fraction measurement, the shape function parameters, and thetheoretical calculations.
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